Pokémon Speak

Pokémon Speak is the tendency of Pokémon characters to communicate by saying their own name. A staple of most Pokémon Smashers, it originates from the Pokémon anime, which was hugely popular when Smash 64 was released, and may or may not be canon to the Pokémon games (where the actual audio cries, except for Pikachu's, consist of low-res animal noises). Newer animated Pokémon works, such as Pokémon Origins, have Pokémon use different animal-like cries instead. The purpose of Pokémon Speak is generally believed to be so that children know the Pokémon's names more easily and know which toys to bug their parents for, which makes it even more annoying for some.

HAL Laboratory also used Pokémon Speak in Pokémon Snap, which was developed and released at about the same time as Smash 64. This shows that HAL most likely took Pokémon Speak to be canon outside of the anime at the time and made it canon to the games in some form, possibly justifying its inclusion in Smash.

While not as widely discussed/noticed, Yoshi also talks this way, since he can only say "Yoshi!" and various baby-like noises.

Some users maintain that Pokémon Speak shouldn't be in Smash anymore due to it not really being canon to the games, and because, admit it, it's kinda annoying and stupid to listen to. In fact, a slight majority of users would rather see Pokémon switch to more animalistic cries, although this has zero chance of being changed.

Predictably, nobody complains about Yoshi only saying his name because it doesn't originate from a lame kiddie cartoon. In fact, the lame kiddie Mario cartoon actually had Yoshi speak in English baby talk.